The Sons of Big Boss was a terrorist group that comprised members of U.S. Special Forces Unit FOXHOUND and the Next-Generation Special Forces, led by Liquid Snake. The group's name derived from the fact that members of the NGSF had received gene therapy to mimic the traits of renowned soldier and former FOXHOUND commander Big Boss, with Liquid being a clone of the man himself. Most of the other FOXHOUND members also shared past connections with Big Boss, having great admiration for the so-called "legendary soldier."

In February 2005, the Sons of Big Boss occupiedShadow Moses Island, during an armed revolt against the U.S. Government. The group demanded that the Government hand over Big Boss's remains so that they could use his DNA to correct genetic mutations in the Genome Soldiers. If their demands were not met, they threatened to use the stolen Metal Gear REX to launch a nuclear strike. They later altered the agreement and demanded one billion dollars in addition to the corpse of Big Boss, planning to turn Shadow Moses into a new Outer Heaven. They also intended to add the FOXDIE vaccine to their list of demands, but were unable to do so due to the actions of ex-FOXHOUND agent Solid Snake, Liquid's genetic twin. The New York Mirror, when reviewing Nastasha Romanenko's book In the Darkness of Shadow Moses: The Unofficial Truth, also speculated that the Sons of Big Boss were a radical right-wing group.